UW, CSU Research: Microbes Accelerate Soil Carbon Loss

November 26, 2012 — New research from
scientists at the University of Wyoming and Colorado State University suggests
that the loss of carbon from soils in response to climate change could be accelerated
by unexpected responses of soil-inhabiting microorganisms.

The study was
published in Ecology Letters, a leading
ecology journal, and the research could play an important role in climate
change prediction models.

"These findings
indicate that climate change could lead to higher rates of soil carbon decomposition,
which releases carbon dioxide into the atmosphere,” says project leader Elise
Pendall, an associate professor of ecosystem ecology in the UW Department of
Botany.

“This would
exacerbate climate change by increasing global warming, because carbon dioxide
is a greenhouse gas,” Pendall says. “We also found that plant productivity is
higher in the simulated future climate, but the microbial responses seem to
offset this effect.”

To explore the
mechanisms behind
the accelerated soil carbon loss under climate change, the
UW and CSU scientists studied the important role played by soil microbial
communities in a manipulative climate change experiment. The Prairie Heating and
CO2 Enrichment (PHACE) experiment was conducted in a grassland area near
Cheyenne.

“In the PHACE experiment, we
used a novel laboratory method that involved inoculating sterile soils with
microbes that have been living under simulated future climates,” says Ming Nie, lead research
author and a postdoctoral research scientist in the UW Department of Botany.
“We asked
the question: Have these microbes changed in their ability to decompose soil
carbon?”

Researchers found
that microbes responded to elevated CO2 and warming by increasing their ability to
degrade soil carbon at warmer temperatures, which can accelerate
soil decomposition and potentially lead to soil carbon losses. The research
suggests that this could eventually diminish sustainability of future plant
growth and ecosystem productivity.

Senior co-author
Matthew Wallenstein, an assistant professor in the Department of Ecosystem
Science and Sustainability at CSU’s Warner College of Natural Resources, says, “This
study shows that soil microbes can respond to climate change in ways that affect
ecosystem functions and can have important consequences for our fragile planet.”

Wallenstein says
this discovery is not predicted by current ecosystem models and shows why it is
vital to understand microbial feedbacks to climate change.

Photo:(from left) Researchers Matthew
Wallenstein from Colorado State University and Elise Pendall and Ming Nie, both
from the University of Wyoming, examine responses of ecosystem below-ground processes
to climate change. (Bryony Wardell Photo)